Field of the Invention
The present invention relates to an image reading apparatus and an image forming apparatus including the image reading apparatus.
Description of the Related Art
Conventionally, some image reading apparatus for use in an image forming apparatus such as a scanner, a printer, and a copier read an image of a document while conveying the document by an auto document feeder (referred to as an ‘ADF’ hereinafter). The image reading apparatus reads the document by an image reading unit while conveying the document between a platen roller and a transparent guide.
In the image reading apparatus, however, there is a case when foreign matters such as toner powder, paper dust, and rubber dust generated in conveying the document are electrostatically attracted to and trapped on the transparent guide. If the foreign matters are happened to stay at a document reading position of the image reading unit in that case, the image reading unit reads the foreign matters while reading the document only to generate striped images (streaky image defect). Then, U.S. Pat. No. 7,616,353 discloses a configuration in which a conductive member is provided on a transparent guide to prevent the transparent guide from being electrostatically charged so as to prevent such image defect.
Meanwhile, U.S. Pat. No. 8,416,476 discloses an image reading apparatus in which an image reading unit is provided within an ADF besides an image reading unit provided on a side of an image reading apparatus body (referred to as a ‘reading apparatus body’ hereinafter), so as to simultaneously read both surfaces of a document being conveyed.
Here, when such a conventional image reading apparatus reads simultaneously the both surfaces of the document, the document is conveyed while sliding the transparent guides respectively provided in the reading apparatus body and the ADF. Then, as shown in FIG. 15, a part of the foreign matters G conveyed together with the document D is frictionally slid between the document D and the transparent guide 401 of the reading apparatus body or the transparent guide 501 of the ADF, and is electrostatically trapped on the transparent guide 401 or 501.
After that, while the document D is conveyed through a gap between the transparent guides 401 and 501 facing each other, the foreign matters G remains electrostatically trapped on the transparent guides 401 and 501. If the foreign matters G is happened to be located at document reading positions of the image reading units 402 and 502 in the reading apparatus body and the ADF, the image reading units 402 and 502 might read the foreign matters G in reading the image from the document D, thus generating striped images.
Then, some of the conventional image reading apparatus are provided with a conductive member 403 such as an aluminum sheet pasted on the transparent guide 401 of the reading apparatus body from a front surface to a back surface thereof with a conductive double-sided tape 404. The conductive member 403 is electrically connected with a casing 405 of the grounded reading apparatus body through the conductive double-sided tape 404. A conductive member not shown is also pasted on the transparent guide 501 of the ADF, and an elastic wire (ground line) or the like composed of conductive material is connected to the conductive member. The elastic wire rod is guided by a bundled wire guide within the ADF and is connected to the casing 405 of the reading apparatus body. Thus, the transparent guide 501 is grounded.
In the case of grounding the transparent guide 501 on the ADF side as described above, however, it is necessary to dispose a guide component for restricting the ground line to wire the ground line within the ADF and to pass the line to the image forming apparatus body (referred to as an ‘apparatus body’ hereinafter), and a length of the ground line needs to be considerably prolonged. As a result, not only it necessitates a complicated configuration for grounding the transparent guide, but also both cost and size of the image reading apparatus may increase.